DESCRIPTION (provided by applicant): The overall goal of this application is to understand the postprandial metabolic response to high vs. low glycemic load meals. Much research has been done on postprandial responses of glucose and insulin to acute feeding of individual foods of varying glycemic index, but most other biomarkers measured in human studies are done in the fasting state. Very little is known about meal effects on biomarkers that may be more directly in the carcinogenesis pathway, such as the insulin-like growth factors. Because frequent eating of meals and snacks places many Americans in the postprandial state for many of their waking hours, understanding meal effects on biomarkers of interest is an important, but understudied, area of research. We propose to test postprandial responses to low- and high-glycemic load meals in 20 individuals who are enrolled in a randomized, cross-over feeding study. In the parent study, participants are free-living but receive all food and beverages from a human nutrition laboratory for two four-week periods. During one feeding period participants are given a low-glycemic load diet and during the other a high glycemic load diet. Fasting bloods are drawn at the beginning and end of each feeding period. For this proposed study, participants will be invited to consume two extra meals (breakfast and lunch) at the end of each feeding period followed by eight hours of serial blood draws to assess the protracted postprandial response of insulin, glucose, IGFI, IGFII, IGFBP1, IGFBP3, free fatty acids, and triglycerides. We believe that this proposed study makes efficient use of an existing well-controlled feeding study and will provide important information on the human metabolic response to various meal patterns. Postprandial glycemic response to 4-week low and high glycemic load diets One way to study how specific foods affect health is to feed people meals with known quantities of nutrients and measure various markers in the blood. This study is designed to compare meals that are low- or high- glycemic load with respect to various biomarkers that are known to be related to various chronic diseases such as cancer. Volunteers enrolled in a randomized cross-over feeding study will be asked to eat two additional meals; we will monitor the postprandial responses by measuring biomarkers in the blood for eight hours after the meals.